During low or normal capacity washer usage the automatic water heater provides adequate hot water for the washers in a laundry, but upon continuous heavy usage of the washers the water heater may prove to be inadequate and as a result the washers will be provided with lukewarm if not cold water. In typical coin operated laundries, one dryer is usually provided for two washers, with about ninety-five percent of the washed laundry generally being dried in the dryers. A system for preheating water for the automatic water heater is shown in a recently issued patent, U.S. Pat. No. 3,771,238, in which a portion of the cold water normally supplied to the water heater is preheated by passing it through coils exposed to the warm vent gases recirculated through the dryer. However, since the vent gas temperature is relatively low, this patented system can do no more than preheat water for the automatic water heater, it cannot heat the water to normal water supply temperatures. Additionally, this system is controlled responsive to water temperature in the automatic water heater rather than responsive to operation of one or more of the dryers. Among the references cited in the previous noted patent is U.S. Pat. No. 3,050,867, which is quite similar but uses water heating coils in the individual vent flues of the dryers, and this system is controlled responsive to flue gas temperature rather than to the temperature of water in an automatic water heater as in the other patent. Another citation in the first noted patent is U.S. Pat. No. 1,731,290, which uses waste heat of a laundry environment for heating water. Other patents include U.S. Pat. No. 3,173,767, directed to a steam heated clothes dryer, and shows steam coils in an upper portion of the dryer for warming drying air which is circulated through the remainder of the dryer. U.S. Pat. No. 2,564,798 has separate compartments for washing, sterilizing, and drying dishes, and has burners for heating water coils, the exhaust of the burners being passed through a large conduit over which drying air is heated.